Outside of AP and McCoy, there isn't a running back in the league that matters anymore.
Ray Rice got 5 carries, and Joe Flacco, I say again, Joe Flacco droppin back 50 times. This is today's NFL.
Running Back is damn near a decoy more than anything, or if they are decent enough in the passing game (Reggie, Sproles) then they can be used that way.
And if you look at the 2014 Draft as of right now, about 10-15 QB's that can come up, and about 35+ receivers that look nice on the way. Not to mention a handful of Tight Ends that will be pass catchers for someone. Maybe, maybe 4-5 running backs that look worthy of anything, and a couple of those fit in the Reggie/Sproles category.
2015 looks to have a couple RB's in Gurley, Yeldon and Duke, but by then it will be so slanted towards passing, even they may not make any sort of impact for a while, unless they can catch the ball.